Page printer facsimile receiver



Sept. 23, 1958 R, HELL 2,853,551

PAGE PRINTER FACSIMILE RECEIVER FiledAug. 8, 195a 2 Sheets-Sheet 1 Sept.23, 1958 R'HELL 2,853,551

PAGE PRINTER FACSIMILE RECEIVER Filed Aug. 8, 1956 2 Sheets-Sheet 2United States Patent PAGE rrnn FACSIMILE RECEIVER Rudolf Hell, Kiel,Germany, assignor to Dr.-Ing. Rudolf Hell K. G., Kiel-Dietrichsdorf,Germany, a German company Application August 8, 1956, Serial No. 602,890

Claims priority, application Germany July 28, 1955 15 Claims. (Cl.178-41) This invention is concerned with a page printer facsimilereceiver and a method of operating it.

The receiver may be of the kind which employs for the recording ofreceived signals a rotatable drum carrying a single or multiple turnprinting spiral. Slightly spaced from the drum is a knife-edge printingmember extending perpendicular to the printing spiral so as to printupon a recording paper, disposed between the drum and the printingmember, small symbol elements. The recording paper is a sheet whichextends from a supply reel and which is stepwise or continuouslyadvanced in a direction perpendicular to the axis of the drum. Thespiral carried upon the drum is continuously inked by an ink roller;carbon paper disposed between the spiral and the recording paper orbetween the printing member and the paper may be used in place of theinking roller. The printing member, responsive to symbol impulsesreceived, is actuated relative to the recording paper by electromagneticor electrodynamic drive means, to press it against the paper and thelatter against the printing spiral, thereby effecting printing of symbolelements upon the recording paper which appear thereon in lines ofpredetermined length.

Instead of using ordinary recording paper, paper impregnated with anelectrolyte, so-called electrochemical paper may be used to producethereon symbol element imprints responsive to passage of current betweena point of the printing spiral and the knife-edge printing member.Special graphitized or metallized paper may also be employed to producevisible imprints thereon responsive to arcing between the printingspiral and the knife-edge printing member.

Other embodiments employ a pointed electrode in place of a printingdrum, which is moved line-by-line crosswise in front of the sheetlikerecording paper, to produce upon the paper visible recordings responsiveto current flow or arcing between the electrode and the drum which isdisposed in back of the paper.

The drawback of prior facsimile page printers requiring the use ofelectrochemically prepared or metallized or graphitized paper is, thatthe use of ordinary unprepared paper is excluded; and the drawback ofprior page printers employing a printing spiral and movable printingmembers is, that they do not permit an increase of the recording speeddue to inertia factors. However, users of facsimile page printers,especially for recording Weather reports, increasingly demand apparatusin which ordinary paper can be used, noting that the use of expensive,particularly prepared special paper is annoying in view of the smoke andbad odor developed during operation and also in view of the necessityfor moistening elec tro-chemical paper prior to operation and dryingthereof after concluding the recording.

The drawback in connection with facsimile page printers adapted forusing ordinary paper, being equipped with a printing spiral which iscontinuously inked, and having movable printing members for respectivelyselecting turns of the printing spiral is, that the electro-magnetically'2 controlled printing members are activated with the picture pointfrequency and, as a consequence, that the printing members due to theirrelatively great inertia,

can be operated only in accordance with a relatively low frequency. Theendeavors are, however, to increase the picture point frequency to about1000 to 1500 cycles; page printers of the indicated type are unsuitablefor the corresponding printing speeds.

The present invention proposes a new system for facsimile receivers,wherein received signals, resulting from scanning of symbol lines in thetransmitter, are recorded successively in color upon an endless tape, bymeans of a printing system, and stored thereon at least for the lengthof a line, the tape being moved about two reels and serving as anintermediate record carrier. The individual stored lines are thereuponsuccessively printed upon a paper sheet, phasally mutually correct, bymeans of a periodically momentarily effective printer mechanism which isactuated relative to the paper sheet in a direction perpendicular to thedirection of advance motion thereof.

In a page printer according to the invention, provided with anintermediate record carrier, the printer mechanism is actuated inaccordance with the line frequency which corresponds to a small fractionof the picture point frequency. There is provided a small printingroller for effecting the recording upon the intermediate record carrier,such roller operating with such a slight inertia that it can easilyfollow higher picture point frequencies of approximately 1000 to 2000cycles.

The various objects and features of the invention will appear from thedescription which will be rendered below with reference to theaccompanying drawings, in which Fig. 1 shows a page printer receiveraccording to the invention which is synchronized with the transmitteronly once, prior to effecting the transmission; and

Fig. 2 illustrates a similar page printer receiver which is synchronizedin accordance with the start-stop principle, by a transmitter whichtransmits periodic line synchronizing signals respectively ahead of orat the end of each line.

In Fig. l, a motor 1 drives over a worm 2 and worm wheel 3 a reel 4 tomove an endless band or tape 6 which is also supported by reel 5uniformly in the direction of the arrow shown on the frontal flight ofthe tape. to rotate a worm Wheel 8 for the purpose of driving the paperadvance drum 9, thereby uniformly moving the record-receiving paper 12,taken from a supply 13, in the direction indicated by arrows. Numerals10 and 11 indicate idler pressure rollers for the paper 12. The paper 12is advanced between the tape 6 and a pressure roller 14 which is closelyadjacent thereto. The gear ratios between the Worm 2 and worm wheel 3and between the worm 7 and the worm wheel 8 are such, that therecord-receiving paper 12 moves during the interval required for themotion of the tape 6 for the length of a printing line, by an amountcorresponding to the spacing between two transmitter scanning lines.Numeral 15 indicates a cross-sectionally S-shaped bar which is ro-.

tatably 'journalled about an axis 16. The printing bar 15 is held innormal position, in which it is not pressed against the tape 6, by meansof a spring 17. The length of the printing bar corresponds to that of aprinted line. Numeral 18 indicates a printer magnet for attracting, uponenergization thereof, the lower leg 19 of the printing bar 15, therebyrotating the bar clockwise about the axis 16 and pressing the knife-edge20 thereof against the tape 6 and the latter against the recording sheet12 which is in engagement with the pressure roller 14.

The motor ll rotates at the same time a worm 7 Numeral 21 indicates anelectromagnetic printing system which is controlled by the transmitter.This system is provided with a member 22 having a knife-edge. Uponenergization of the system responsive to a signal impulse received fromthe transmitter, the knife-edge 22 will press the tape 6 againstthe'knife-edge of a slowly rotating inking wheel 23. is accomplished bya slowly rotating and periodically axially moving inking roller 24.Numeral 25 indicates a slowly rotating felt roller which rotates in adirection opposite to the direction of rotation of the reel 4. The feltroller 25 cancels the symbol elements impressed upon the tape 6 after aline thereof has been printed on the record-receiving paper 12. The tape6 is made of rubber cloth or a foil of synthetic material adapted toaccept color imprints and transfer them to the record-receiving sheet12. The shaft 26 for the reel 4 and the worm wheel 3 carries one part 27of a slip clutch, the other clutch part 28 carrying a cam 29 beingcarried by a shaft 32 to which is fastened a cam disk 30 having a rise31. The cam 31 upon rotating effects periodic closure of contacts 33 formomentarily energizing the printer magnet 18 by current from a battery34. Numeral 35 indicates a detent lever which is biased counterclockwiseby a spring 37 with its left hand end in engagement with a stop 38,thereby limiting the stroke of the corresponding end of the lever.

Numeral 39 indicates a transmission line to which is connected areceiver amplifier 40, followed by an amplitude filter 41 acting as amaximum value limiter to keep from the printing system 21 the phasesignal and the synchronizing signals, respectively. The incoming symbolsignals are rectified in the rectifier 42 and reach the printing system21. An amplitude filter 43 is provided in parallel with the maximumvalue limiter 41, acting as a minimum value limiter, and connected tothe output of the amplifier 40. The limiter 43 keeps symbol signals ofsmaller amplitude from a receiver relay E which is connected thereto byway of a rectifier 44. The relapy for starting the operation of thereceiver is shown at Responsive to release of a start signal by thetransmitter, relay B will energize and contacts 6 will be closed toclose a circuit for relay R from a battery 45, relay R closing a holdingcircuit for itself at contact r At r relay R closes a circuit for themotor 1. At contact 2 relay E connects current from a battery 46 toenergize the holding magnet 47 which attracts the right hand end of thedetent lever 35, thereby rotating such lever clockwise to position itsleft hand end in front of the cam 29 of the lower part 28 of the slipclutch 2728, thus holding the lower part 28 of the slip clutch andtherewith the cam disk 39 in a definite start position.

This start or initial position is such as to cause energization of theprinting magnet always at the instant when the beginning of a line ofsymbol elements imprinted and stored upon the tape 6 has reached theright hand end of the printing bar 15. The transmitter and the receivermotors must with this single phase-correction at the beginning oftransmission operate in synchronisrn for the duration of signaltransmission so as to assure that the start and the end of all lines areexactly in alignment.

Upon conclusion of the start signal from the transmitter, the detentmagnet 47 will be deenergized, releasing the lever 35 to permit instantrotation of the cam disk 39. The recording starts now and the printermechanism l-18 is controlled in phase.

It is not necessary that the tape speed of the page printer correspondsto the scanning speed of the transmitter; the first may indeed be higheror lower than the second. If the advance speed of the recording sheet isin the same ratio increased or decreased relative to the advance speedof the transmitter scanning device, magnified or reduced documents canbe received with the The inking of the wheel 23 page printer. This is ofsignificance, for example, in the case of facsimile transmitters forlarge Weather charts which have to be received on a smaller scale withsmall telegram size page printers. It is for this purpose necessary,outside of the correct phase position of the received image lines, thatthe ratios between tape and scanning speed on the one hand and betweenthe advance speeds on the other hand, are constant and one correspondingto the other, so as to obtain a document in the receiver whichcorresponds geometrically to the transmitted document.

It will be seen from the foregoing explanations that a phase correctiontakes place in the arrangement according to Fig. 1, controlled by thereceiver, only once upon beginning of the transmission. In thearrangement according to Fig. 2, there is a periodically recurring phasecorrection respectively ahead of or at the conclusion of each imageelement line, the facsimile transmitter being assumed to transmitperiodic line synchronizing signals.

The advantage of line synchronization is, that complete synchronismbetween the transmitter and receiver motors is not necmsary; it issufficient if synchronism exists for the relatively short interval ofscanning and recording a single line. The R. P. M. of the two drivemotors may mutually differ to some extent during the transmission of thedocument to be recorded and synchronizing means for the drive motors cantherefore be dispensed with.

An example of line synchronization is shown in Fig. 2, the details ofwhich correspond largely to those shown in Fig. 1. Corresponding partsare similarly referenced.

The difference as compared with Fig. 1 resides in deriving rotation of ashaft 5t) from the rotation of shaft 26 by means of different gearwheels 43 and 4 9. The shaft 50 drives over the slip clutch 2728 theshaft 32 carrying the cam disk 30. Depending on fluctuations in the R.P. M. of the drive motor 1, the shaft 50 will be rotated somewhat fasterthan the shaft 26. In accordance with the start-stop principle, theperiodic line synchronizing impulses from the transmitter will correctthe phase correct position of the cam disk 30 periodically, respectivelyahead of and at the conclusion of each line. The cam disk 30 accordinglydoes not rotate with constant R. P. M. but intermittently. The detentmagnet 47 is momentarily energized responsive to each incomingsynchronizing impulse, whereupon the detent lever 35 frees the cam diskfor one revolution. Upon conclusion of one revolution, the cam disk 30is held by the releasing detent lever 35 until the next synchronizingsignal arrives. The operation is thereupon repeated.

Changes may be made within the scope and spirit of the appended claims.

I claim:

1. A page printer facsimile receiver comprising an endless tapeoperating as an intermediate record carrier, at record-receiving sheet,means for moving said intermediate record carrier, means for moving saidrecord-receiving sheet in a direction perpendicular to the direction ofmotion of said intermediate record carrier, operating means forcontinuously successively recording in color upon said intermediaterecord carrier symbol elements corresponding to incoming signalsreceived from a transmitter and belonging to successive lines of symbolsto be recorded upon said record-receiving sheet, a printing mechanism,control means for periodically actuating said printing mechanism for thepurpose of simultaneously printing on said record-receiving sheet groupsof symbol elements recorded upon said intermediate record carrier andbelonging respectively to successive lines, and means for cancellingsymbol elements recorded upon said intermediate record carrier afterprinting thereof line for line on said record-receiving sheet.

2. Apparatus according to claim 1, comprising means for periodicallyactuating said control means responsive to phase signals received fromthe transmitter.

3. Apparatus according to claim 1, comprising two rotatable reels formovably supporting said endless tape constituting said intermediaterecord carrier, an electromagnetic recording system disposed relative toone flight of said carrier constituting said operating means, arotatable roller disposed relative to the identical flight of saidcarrier constituting said cancelling means, a printing bar forming partof said printing mechanism disposed relative to the other flight of saidcarrier, the length of said printing bar corresponding to the length ofa line of symbol elements to be printed on said recordreceiving sheet,and an electromagnet also forming part of said printing mechanism forperiodically actuating said printing bar to move the correspondingflight of said carrier against said record;receiving sheet for thepurpose of printing thereon symbol elements recorded on said carrier.

4. Apparatus according to claim 3, comprising gear means for rotatingone of said reels to move said intermediate record carrier, gear meansfor moving said record-receiving sheet, and motor means for actuatingsaid gear means, the gear ratios of said gear means being such as tocause said intermediate record carrier to move at a speed which exceedsthe speed of movement of said record-receiving sheet by an amountcorresponding for each line length to the spacing between lines to berecorded on said sheet.

5. Apparatus according to claim 4, comprising contact means forgoverning the operation of said electromagnet, a cam for governing theactuation of said contact means, gear means including a friction clutchfor operating said cam, and a device for governing the actu ation ofsaid friction clutch comprising a holding magnet controlled by signalsreceived from the transmitter, said holding magnet being responsive toreceipt of a signal effective to release said cam for one revolution toeflect actuation of said contact means.

6. Apparatus according to claim 5, comprising a receiver relay, circuitmeans for receiving signals from said transmitter, said circuit meanscomprising two branches each containing an amplitude filter and arectifier, means for connecting one of said branches with said operatingmeans, and means for connecting the other branch with said receiverrelay.

7. Apparatus according to claim 1, comprising a tape made of rubbercloth constituting said intermediate rec ord carrier.

8. Apparatus according to claim 1, comprising a tape constituting saidintermediate record carrier, said tape being made of synthetic foilmaterial adapted to accept pigment and to transfer it unto saidrecord-receiving sheet.

9. Apparatus according to claim 1, comprising electromagnetic means foractuating said printing mechanism.

10. Apparatus according to claim 1, comprising a common drive mechanismfor said record-recording sheet and for said intermediate recordcarrier, respectively, and means controlled by said drive mechanism forperiodically actuating said printing mechanism 11. Apparatus accordingto claim 1, comprising an electromagnet for actuating said printingmechanism, contact means for controlling the operation of saidelectromagnet, and rotatable cam means for controlling the actuation ofsaid contact means.

12. Apparatus according to claim 1, comprising an electromagnet foractuating said printing mechanism, contact means for controlling theoperation of said electromagnet, rotatable cam means for controlling theactuation of said contact means, a slip clutch for rotating said cammeans, detent means for controlling said slip clutch, a magnet forcontrolling said detent means, and circuit means controlled from atransmitter for controlling said magnet for causing said slip clutch torotate said cam means into phasally correct start position.

13. Apparatus according to claim 1, wherein said means for periodicallyactuating said printing mechanism comprises a control element, a slipclutch, detent means for said slip clutch including a detent magnet,said drive mechanism comprising a drive motor, circuit means govcrnedfrom a transmitter for transmitting synchronizing signals, meanscontrolled by said drive mechanism for rotating said control elementthrough the medium of said slip clutch at a speed of revolution whichexceeds the maximal fluctuation in the speed of revolution of said drivemotor as compared with the sequence frequency of said synchronizingsignals, said detent magnet being operative to release said controlelement for one revolu- 'tion responsive to each synchronizing signaland to arrest rotation thereof at the conclusion of each revolution foran interval until the next synchronizing signal is received.

14. Apparatus according to claim 1, wherein said intermediate recordcarrier is moved at a speed corresponding to the scanning speed of thetransmitter, and wherein said record-receiving sheet is moved at a speedcorresponding to the speed of scanning-advance of the transmitter.

15. Apparatus according to claim 1, wherein the ratios of the speed ofsaid intermediate record carrier to the scanning speed of thetransmitter and of the speed of advance of said record-receiving sheetto the scanningadvance speed of the transmitter are respectivelyconstant and mutually identical.

References Cited in the file of this patent UNITED STATES PATENTS

